U.S. patent application number 11/975196 was filed with the patent office on 2008-04-03 for means and method for the accurate placement of a stent at the ostium of an artery.
This patent application is currently assigned to Ostidl Solutions, LLC. Invention is credited to David R. Fischell, Robert E. Fischell, Tim A. Fischell, Mark E. Zyzelewski.
Application Number | 20080082155 11/975196 |
Document ID | / |
Family ID | 39261987 |
Filed Date | 2008-04-03 |
United States Patent
Application |
20080082155 |
Kind Code |
A1 |
Fischell; Robert E. ; et
al. |
April 3, 2008 |
Means and method for the accurate placement of a stent at the
ostium of an artery
Abstract
Disclosed is an ostial stent positioner that has the form of a
wire for most of its length and having a short cylinder with a
longitudinal slit and expandable legs situated at the positioner's
distal end. The slit cylinder with its attached wire acts as an
introducer sheath to introduce a stent delivery system with a stent
into the artery that is to be stented. A second aspect of the
present invention is a method for accurately placing a stent at the
ostium of an artery that would have an ostial stenosis. Examples of
such arteries that have ostial stenoses are the right and left main
coronary arteries, a saphenous vein graft as used in coronary
bypass surgery and the renal arteries. Also disclosed are designs
for the slit cylinder that provides a variable diameter so as to
fit snugly within guiding catheters having different inside
diameters.
Inventors: |
Fischell; Robert E.;
(Dayton, MD) ; Fischell; Tim A.; (Kalamazoo,
MI) ; Fischell; David R.; (Fair Haven, NJ) ;
Zyzelewski; Mark E.; (Kalamazoo, MI) |
Correspondence
Address: |
Robert E. Fischell
14600 Viburnum Drive
Dayton
MD
21036
US
|
Assignee: |
Ostidl Solutions, LLC
|
Family ID: |
39261987 |
Appl. No.: |
11/975196 |
Filed: |
October 18, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11442719 |
May 30, 2006 |
|
|
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11975196 |
Oct 18, 2007 |
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Current U.S.
Class: |
623/1.11 |
Current CPC
Class: |
A61F 2002/821 20130101;
A61F 2/95 20130101; A61F 2250/0098 20130101 |
Class at
Publication: |
623/001.11 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1. An introducer sheath type of ostial stent positioner for
facilitating the placement by an operator of the proximal end of a
stent within .+-.2 mm of the ostial plane of an artery that has an
ostial stenosis, the positioner having a wire extending for most of
its length that is attached to a variable diameter cylinder that
has an adjustable outer diameter that becomes essentially the same
dimension as the inside diameter of a guiding catheter into which
the cylinder is placed, the variable diameter cylinder being
designed to exert a gentle outward force against the interior wall
of the guiding catheter, the wire extending for most of the length
of the positioner having a distal section and a proximal section
with the distal section being shorter in length and smaller in
diameter as compared to the proximal section of the wire, the
variable diameter cylinder also being fixedly attached to at least
two expandable distal legs that end with radiopaque feet that form
a distal plane when they are pushed in a distal direction out of
the distal end of the guiding catheter and against the interior
wall of the aorta, the positioner being designed for placement of
the distal plane of the radiopaque feet to be substantially
co-planar with the ostial plane of the artery when the ostial stent
positioner is urged forward in a distal direction after the
expandable distal legs have been expanded radially outward beyond
the distal end of the guiding catheter through which the positioner
can be placed.
2. The positioner of claim 1 where the variable diameter cylinder
is adapted to be placed into guiding catheters having diameters
that lie between 4 Fr and 14 Fr.
3. The positioner of claim 1 where the wire has a handle at its
proximal end to facilitate the handling of the positioner by the
operator.
4. The positioner of claim 3 where the handle is formed from a
plastic material having a color that is distinctly different from
the gray color of a guide wire.
5. The positioner of claim 1 where the expandable legs have feet
that are formed from a radiopaque metal or coated with a radiopaque
metal.
6. The positioner of claim 5 where the feet on the expandable legs
have an outside diameter when expanded that lies between 4 and 15
mm.
7. The positioner of claim 1 where the positioner has expandable
legs that are formed from a combination of a plastic material and a
metal, the combination being generally radiopaque.
8. The positioner of claim 1 where the variable diameter cylinder
has expandable legs that are generally in the shape of a flower
that has at least two petals.
9. The positioner of claim 8 where the cylinder's expandable legs
form at least four petals.
10. The positioner of claim 1 where the variable diameter cylinder
of the ostial stent positioner has a wedge-like surface for easy
placement into the distal end of a guiding catheter, the wedge-like
structure having an angle "A" that lies between 10 and 30
degrees.
11. The positioner of claim 1 where the variable diameter cylinder
of the ostial stent positioner has a slit in its outer
circumferential surface so as to have an outside diameter that is
variable depending on the inside diameter of the guiding catheter
into which the cylinder is inserted.
12. The positioner of claim 11 where the slit cylinder that is
attached to the expandable legs has an angle where the slit
cylinder is joined to the distal wire section that is less than 30
degrees.
13. The positioner of claim 1 where the variable diameter cylinder
of the ostial stent positioner has a helical, flat wire, cylinder
structure so as to have an outside diameter that is variable
depending on the inside diameter of the guiding catheter into which
the cylinder is inserted.
14. The positioner of claim 1 where both the distal and proximal
sections of the wire extending for most of the length of the
positioner is formed from the metal Nitinol.
15. The positioner of claim 1 where the variable diameter cylinder
is formed from a shape memory alloy.
16. The positioner of claim 15 where the shape memory alloy that is
used to form the variable diameter cylinder is super elastic
Nitinol.
17. A method for placing the proximal end of a stent within an
artery that has an ostial stenosis so that the stent's proximal end
is positioned within .+-.2 mm of the artery's ostial plane, the
method including the following steps: a) placing an introducer
sheath type of ostial stent positioner that has at least two
expandable distal legs into a guiding catheter with the expandable
legs in an unexpanded state, the expandable legs having at least
some portion that is radiopaque and the expandable legs being
attached to a cylinder that is less than 10% as long as the length
of the guiding catheter and the positioner having a wire for most
of its length that has a smaller diameter distal section as
compared to the diameter of the longer proximal section; b) causing
the expandable legs to expand in a region beyond the distal end of
the guiding catheter; c) urging the ostial stent positioner in a
forward, distal direction so that a distal plane of the expanded
legs is placed substantially co-planar with the ostial plane of the
artery that has the ostial stenosis; and d) positioning a stent
within the stenosis of the artery so that the stent's proximal
radiopaque marker band is situated relative to the distal plane of
the expanded legs of the positioner so that the stent's proximal
end is located within .+-.2 mm of the ostial plane of the artery
when the stent is deployed.
18. The method of claim 17 where the positioner's expanded legs are
generally shaped in the form of a flower with at least two
petals.
19. The method of claim 17 where the expanded legs have at least
some portion that is formed from a radiopaque metal or coated with
a radiopaque metal.
20. The method of claim 17 where the expanded legs are attached to
a variable diameter cylinder that is formed from a shape memory
alloy.
21. The method of claim 20 where both the expanded legs and the
variable diameter cylinder are both formed from a shape memory
alloy.
22. The method of claim 17 where the cylinder is a variable
diameter cylinder that seeks an outside diameter that is
substantially the same as the inside diameter of the guiding
catheter into which the variable diameter cylinder is inserted.
23. The method of claim 22 where the variable diameter cylinder is
a slit cylinder.
24. An introducer sheath type of ostial stent positioner for
facilitating the placement by an operator of the proximal end of a
stent within .+-.2 mm of the ostial plane of an artery that has an
ostial stenosis, the positioner having a wire extending for most of
its length that is attached to a variable diameter cylinder that is
adapted to be placed within a guiding catheter, the outside
diameter of the variable diameter cylinder being substantially the
same as the inside diameter of the guiding catheter into which the
variable diameter cylinder is inserted, the length of the variable
diameter cylinder being less than 10% of the length of the guiding
catheter, the variable diameter cylinder also being attached to at
least two expandable distal legs that end with radiopaque feet that
form a distal plane when they are pushed in a distal direction out
of the distal end of the guiding catheter and against the interior
wall of the aorta, the positioner being designed for placement of
the distal plane of the radiopaque feet to be substantially
co-planar with the ostial plane of the artery when the ostial stent
positioner is urged forward in a distal direction after the
expandable distal legs have been expanded radially outward beyond
the distal end of the guiding catheter.
25. The positioner of claim 24 where the variable diameter cylinder
is a slit cylinder.
26. A method for placing the proximal end of a stent within an
artery that has an ostial stenosis so that the stent's proximal end
is positioned within .+-.2 mm of the artery's ostial plane, the
method including the following steps: a) placing an introducer
sheath type of ostial stent positioner that has at least two
expandable distal legs with radiopaque feet into a guiding catheter
with the expandable legs in an unexpanded state, the legs being
attached to a short cylinder; b) positioning the guiding catheter
with its distal section within the aorta aligned generally
perpendicular to the ostial plane; c) causing the expandable legs
to expand in a region beyond the distal end of the guiding
catheter; d) moving the ostial stent positioner in a forward
direction so that the distal plane of the feet of the expanded legs
is placed substantially co-planar with the ostial plane of the
artery that has the ostial stenosis; and e) positioning a stent
within the stenosis of the artery so that the stent's proximal
radiopaque marker band is situated relative to the distal plane of
the expanded legs of the positioner so that the stent's proximal
end is located within .+-.2 mm of the ostial plane of the artery
when the stent is deployed.
27. The method of claim 26 where the positioner's expanded legs are
generally shaped in the form of a flower with at least two
petals.
28. The method of claim 26 where the feet of the expanded legs have
at least some portion that is formed from a radiopaque metal or
coated with a radiopaque metal.
29. The method of claim 26 where the short cylinder to which the
expanded legs are attached is a variable diameter cylinder.
30. The method of claim 29 where both the expanded legs and the
variable diameter cylinder are both formed from a shape memory
alloy.
Description
REFERENCE TO A PREVIOUS PATENT APPLICATION
[0001] This is a continuation-in-part application of the patent
application Ser. No. 11/442,719 filed on May 30, 2006.
FIELD OF USE
[0002] This invention is in the field of devices for placing stents
within a stenosis that extends to or near the ostium of an
artery.
BACKGROUND OF THE INVENTION
[0003] Although most stenoses do not occur at the ostium of an
artery, there are thousands of cases each month where the mouth of
an artery (the ostium) is substantially obstructed at its aortic
take-off; this is called an aorto-ostial lesion. In such cases, the
interventional cardiologist or radiologist is frequently unable to
place the stent's proximal end within .+-.2 mm of the ostial plane.
Two types of incorrect stent positions are (1) when the stent's
proximal end extends more than 2 mm into the aorta, and (2) when
the stent's proximal end is placed more than 1-2 mm into the artery
distal to the ostial plane.
[0004] In U.S. Pat. No. 6,458,151, F. S. Saltiel describes an
ostial stent positioning device. However, the most important
feature of such a device; namely, and expandable distal portion
that touches the wall of the aorta near the ostium of the artery to
be stented is not optimized for easy usage of such a device.
Furthermore, the Saltiel design is essentially a cylindrical sheath
within the guiding catheter which sheath extends for the entire
length of the guiding catheter. Such a design would have an
incredible amount of friction between the cylindrical sheath and
the interior wall of the guiding catheter that would make it very
difficult to operate. In addition, the Saltiel design would
substantially obstruct the internal cross-section of the guiding
catheter along its entire length, limiting the injection of
contrast material, and the passage of guide wires, balloon
catheters, and/or stents.
[0005] In U.S. Pat. No. 5,749,890, A. Shaknovich utilizes a stent
mounted on a catheter that has an inflatable section that touches
the wall of the aorta in the vicinity of the ostium of the artery
that is to be stented. Such a design precludes an accurate stent
positioning system that can be used with the stent delivery system
of any manufacturer.
SUMMARY OF THE INVENTION
[0006] A first aspect of the present invention is an ostial stent
positioner that has the form of a wire for most of its length and
having a short cylinder with expandable legs situated at the
positioner's distal end. The cylinder with its attached wire acts
as an introducer sheath to introduce a stent delivery system with a
stent into the artery that is to be stented. A second aspect of the
present invention is a method for accurately placing a stent at the
ostium of an artery that would have an ostial stenosis. Examples of
such arteries that have ostial stenoses are the right and left main
coronary arteries, a saphenous vein graft as used in coronary
bypass surgery and the renal arteries. Each of these arteries has
an ostium situated at the aorta.
[0007] The preferred method for using this invention would be to
first back-load the ostial stent positioner within a guiding
catheter. A guide wire could then be loaded through the guiding
catheter, and through the pre-deployed ostial positioning system
that had already been placed within the guiding catheter. The
guiding catheter would be advanced over the guide wire into the
aorta. The next action would be to place the guiding catheter
through the aorta in a conventional manner so that its distal end
will be engaged within or near the ostium of the artery that is to
be stented. The guide wire would then be advanced through the
guiding catheter until its distal end was placed distal to the
stenosis. If pre-dilitation of the ostial stenosis was needed, a
balloon angioplasty catheter would be advanced over the guide wire
and through the guiding catheter and the catheter's balloon would
be inflated to pre-dilate the stenosis. After the balloon
angioplasty catheter was removed from the guiding catheter (or if
no pre-dilatation was required) then a stent delivery system with
the appropriately sized stent would be advanced over the guide wire
until the stent's proximal end lay at or distal to the ostium of
the artery. The stent delivery system would typically have its
proximal radiopaque marker band placed distal to the ostial plane
of the artery to be stented. While retaining the guide wire and a
distal portion of the stent delivery system in the artery, the
guiding catheter with the positioner inside would then be pulled
back a short distance into the aorta. The positioner would then be
advanced until its expandable legs at the positioner's distal end
extended beyond the guiding catheter's distal end, thus allowing
the expandable legs to expand. The guiding catheter would then be
advanced until its distal end surface pushes gently against the
positioner's expandable legs to engage the legs against the wall of
the aorta and generally align the legs at the ostium of the artery
that is to be stented. The plane of the "feet" which are located at
the distal ends of the expandable legs, would then be situated at
the artery's ostial plane. The outer diameter of the feet would be
larger than the diameter of the artery to be stented. Since the
expandable legs would have feet that would be formed from a
material that included a radiopaque substance or from a metal that
is coated with or made from a radiopaque metal, the interventional
cardiologist who is performing this procedure would have a clear
angiographic/fluoroscopic marker of the ostial plane of the artery
that is to have a stent placed within the ostial stenosis of that
artery. The interventional cardiologist would then pull the stent
delivery system back until the proximal radiopaque marker band
within the balloon of the stent delivery system was aligned
appropriately relative to the radiopaque feet of the expandable
legs. The balloon would then be inflated to deliver the stent
accurately at the ostial stenosis with the stent's proximal end
lying within 2 mm of the ostial plane of the artery (typically just
proximal to the true ostial plane). It is expected that an
experienced interventional cardiologist could place the proximal
end of the stent within 1.0 mm and just proximal to the ostial
plane.
[0008] In a prior application one embodiment of this invention was
described that requires a separate introducer device that is used
to place the positioner into the guiding catheter. This
continuation-in-part application teaches an improved embodiment of
the invention that allows the sheath-like ostial stent positioner
to be placed into the guiding catheter without requiring a separate
introducer device.
[0009] The main object of this invention is to describe a means and
method for accurately placing the proximal end of a stent within
.+-.2 mm of the ostial plane of an artery that has a stenosis
located at or near the ostium of that artery.
[0010] Another object of this invention is to place the proximal
end of a stent within .+-.2.0 mm of the ostial plane of an artery
that has a stenosis located at or near the artery's ostium.
[0011] Still another object of the present invention is to teach a
method for accurately placing a stent within an ostial
stenosis.
[0012] Still another object of the present invention is to utilize
a variable diameter slit cylinder to which the expandable legs are
connected, which variable diameter cylinder is designed to expand
radially outward so as to create gentle contact between the
cylinder's outer surface and the interior surface of the guiding
catheter.
[0013] Still another object of this invention is to have the
expandable legs go out to an angle as great as 90 degrees relative
to the axis of the positioner so as to fit most smoothly against
the wall of the aorta.
[0014] Still another object of this invention is to have the wire
that joins to the slit cylinder have a colored handle at its most
proximal section and have a decreased wire thickness for the length
of the wire that is closest to the slit cylinder so as to have
increased flexibility at that portion that lies in the curved
section of the guiding catheter.
[0015] These and other objects and advantages of this invention
will become obvious to a person of ordinary skill in this art upon
reading the detailed description of this invention including the
associated drawings as presented herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a side view of a Touhy-Borst fitting, a guiding
catheter and an ostial stent positioner that acts as an introducer
sheath for placing the proximal end of a stent in close proximity
to the ostial plane of an artery that has an ostial stenosis.
[0017] FIG. 2 is a longitudinal cross section of a distal portion
of the ostial stent positioner located within the guiding catheter
showing the expandable legs in their folded state.
[0018] FIG. 3 is a cross section of the distal portions of the
guiding catheter, a stent on a stent delivery system and the
positioner showing the distal end plane of the feet of the
expandable legs placed at the ostial plane of an artery having an
ostial stenosis.
[0019] FIG. 4 is a top view of an alternate embodiment of the
present invention using a slit cylinder with expandable legs.
[0020] FIG. 5 is an end view of the embodiment of FIG. 4.
[0021] FIG. 6 is the side view of the embodiment of FIG. 4.
[0022] FIG. 7 is a perspective view of an alternative embodiment of
the invention using a helical coil cylinder for improved
flexibility.
[0023] FIG. 8 is a side view of an alternative embodiment of the
present invention showing legs that extend to be at an angle of
approximately 90 degrees relative to the longitudinal axis of the
positioner when the legs are pushed against the wall of the aorta
and also showing a smaller diameter for the wire where it attaches
to the slit cylinder.
DETAILED DESCRIPTION OF THE INVENTION
[0024] FIG. 1 is a side view of a catheter system 10 whose object
is to accurately place a stent with its proximal end being situated
close to the ostial plane of an artery having an ostial stenosis.
The catheter system 10 includes the guiding catheter 40 and an
ostial stent positioner 17 that has a wire 11 which connects a
small diameter handle 12 to a cylinder 16 (shown in FIG. 2) which
has expandable distal end legs 14 with radiopaque feet 15. The
guiding catheter 40 that has a proximal Luer fitting 41 that is
joined to a Touhy-Borst fitting 30. When the feet 15 are fully
expanded, the diameter "D" would typically be between 4 and 10 mm
for coronary artery stenting and between 5 and 15 mm for stenting a
renal artery. When the expandable legs 14 with radiopaque feet 15
are fully expanded they would have the general appearance of the
petals of a flower. When the legs 15 are pushed forward beyond the
distal end of the guiding catheter 40, they expand radially outward
as shown in FIGS. 1 and 3 from the force of the end of the guiding
catheter pushing on the legs 14. When the handle 12 is pulled back,
the legs 15 are retracted into the guiding catheter 40 and then the
positioner 17 can be pulled out of the guiding catheter 40 after
the stent has been placed into the ostial stenosis.
[0025] The Touhy-Borst fitting 30 has an adjustable seal fitting 31
(which is a hemostasis valve) that can initially be slightly
loosened to allow the positioner 17 to be advanced or pulled back
through the guiding catheter 40 without excessive blood leakage.
When the expandable legs 14 are in their correct position for
placement at the ostial plane of a stenosed artery, (as seen in
FIG. 3) the adjustable seal fitting 31 can be tightened to hold a
fixed position of the legs 23 relative to the guiding catheter 40
during stent deployment. The Luer fitting 32, being in fluid
communication with the lumen of the guiding catheter 40, can be
used for flushing the lumen with saline solution and/or for
injecting contrast medium. The Luer connector 33 is used to form a
removable fluidic seal with the Luer fitting 41 of the guiding
catheter 40.
[0026] FIG. 2 is an enlarged cross section of the distal portions
of the guiding catheter 40 and the positioner 17. The positioner 17
is shown with its expandable legs 14 in their unexpanded state
within the guiding catheter 40. In this state, the guiding catheter
40 can be advanced through an introducer sheath at the patient's
groin until its distal end is within the ostium of the artery that
is to be stented. Furthermore, in this state, both a guide wire and
a stent delivery system can be advanced through the guiding
catheter 40 and positioner 17 and through the ostial stenosis. The
fixed diameter cylinder 16 is attached at its proximal end to the
wire 11 and at its distal end to each of the four legs 14. Although
3 legs 14 (of an actual 4 legs) are shown in FIG. 2, as few as 2 or
as many as 16 of petal-like legs 14 could be used for an effective
array of expandable legs 14.
[0027] FIG. 3 is a cross section of a distal portion of the
catheter system 10 shown with the distal plane 45 of the radiopaque
feet 15 placed at the ostial plane of a stenosed artery. The feet
15 are attached to the expandable legs 14 that are attached to the
cylinder 16 which has its position within the guiding catheter 40
adjusted by means of the wire 11. Any such placement of the feet 15
can be defined as having their distal plane 45 "co-planar" with the
ostial plane of the artery that has an ostial stenosis. FIG. 3 also
shows a guide wire 26 placed through the stent delivery system 20
which has a shaft 21, a proximal radiopaque marker band 24, a
distal radiopaque marker band 25 and a stent 23 mounted onto a
balloon 22. The ostial stent positioner 17 would be designed to
introduce essentially any commercially available stent delivery
system 20 into an arterial stenosis. Thus, any interventional
cardiologist could use the positioner 17 with any stent delivery
system that he or she favors. FIG. 3 also shows how the guiding
catheter 40 can be used to gently push the feet 15 against the wall
of the aorta at the ostium of the stenosed artery. It is also
possible to push the feet 15 against the wall of the aorta by
pushing the positioner 17 in a distal direction without the
assistance of the guiding catheter 40.
[0028] At the start of the stenting procedure, a distal portion of
the ostial stent positioner 17 would be positioned as shown in FIG.
2 with the expandable legs 14 placed inside the guiding catheter
40. The catheter system 10 and the guide wire 26 could then be
advanced through a conventional introducer sheath (not shown)
typically placed at the groin of the patient into whom the stent 23
is to be placed. A 0.014 inch diameter guide wire 26 would be
placed into and through the ostial stenosis and the guiding
catheter 40 would be advanced until its distal tip was placed
through the arterial ostium. The stent delivery system 20 would
then be advanced over the guide wire 26 and through the guiding
catheter 40 and positioner 17 until the proximal radiopaque marker
band 24 was positioned just distal to the ostium of the stenosed
artery. The guiding catheter 40 would then be pulled back into the
aorta. The positioner 17 (which was already back loaded into the
guiding catheter 40) would then be advanced through the guiding
catheter 40 until the expandable legs 14 extended out of the distal
end of the guiding catheter 40. The guiding catheter 40 would then
be pushed gently forward in a distal direction so as to obtain the
configuration as generally shown in FIG. 3.
[0029] With the configuration as shown in FIG. 3, the
interventional cardiologist would be able to clearly visualize the
distal plane 45 of the radiopaque feet 15 and also visualize the
proximal radiopaque marker band 24. When the radiopaque marker band
24 is pulled backward until it is co-planar with feet 15, then the
proximal end of the stent 23 would be placed within .+-.2 mm of the
plane of the ostium of the vessel which is to be stented. The
balloon 22 would then be inflated to deliver the stent 23 into the
ostial stenosis. Thus, an interventional cardiologist should be
able to readily place the proximal end of the stent 23 within .+-.2
mm of the ostial plane. With some experience, it is expected that
the proximal end of the stent 23 could be placed within at least
.+-.1.0 mm of the ostial plane and probably within .+-.0.5 mm. The
optimum placement of the proximal end of the stent 23 is that it
extends approximately 0.5 mm into the lumen of the aorta.
[0030] Although one method for accurately placing the stent 23 into
an ostial stenosis has been described herein, it should be
understood that there are several other ways that the present
invention could be used to provide accurate stent positioning
within an ostial stenosis. For example, the guiding catheter 40
with the positioner 17 in place as shown in FIG. 2 could first be
placed over a 0.035 inch diameter guide wire and into the lumen of
the ostial stenosis. That larger diameter guide wire could then be
removed and the 0.014 inch diameter guide wire 26 could be placed
through the stenosis. The stent delivery system 20 could then be
advanced over that guide wire 26 and positioned as shown in FIG. 3.
The guiding catheter could then be pulled back and the expandable
legs 14 could then be deployed as described herein. An important
feature of the system 10 is that the guiding catheter 40 and
positioner 17 could be held to be motionless while the guide wire
26 or the stent delivery system 20 could be advanced forward or
pulled back to obtain an accurate positioning of the stent 23
within the ostial stenosis.
[0031] FIGS. 4, 5 and 6 illustrate an alternative embodiment ostial
stent positioner 50 utilizing a slit cylinder 56 that would replace
the fixed diameter cylinder 16 of FIGS. 2 and 3. The slit cylinder
56 is designed to join to a wire 51 that is equivalent to the wire
11 of FIGS. 1, 2 and 3, which wire 51 is used to move the ostial
stent positioner 50 within the guiding catheter 40. The wire 11 of
FIGS. 1, 2 and 3 was a conventional small diameter, round wire. The
wire 51 of FIGS. 4 and 6 is a flat wire. It should be understood
that the term "wire" should include any structure whose cross
section is round or a small diameter cylinder or a flat wire or a
wire whose cross section is an arc of a circle that is less than
270 degrees. The attachment of the wire 51 to the slit cylinder 56
can be by means of welding, soldering or (with a somewhat different
configuration) by means of a biocompatible adhesive. It is also
conceived that the slit cylinder 56 and the wire 51 can be formed
from a single piece of metal. The slit 57 of the slit cylinder 56
provides a spring-like action to allow the slit cylinder 56 to have
a slight outward force against the inner wall of the guiding
catheter 40. The outside diameter of the slit cylinder 56 when free
in air would have a diameter that is slightly larger than the
inside diameter of the largest diameter guiding catheter 40 that
would be use for a particular procedure. But the slit 57 would
allow the outside diameter of the slit cylinder 56 to compress to
fit into any size guiding catheter that would typically be used for
ostial stenting. The slit 57 would have a width "S" (as seen in
FIG. 4) that is typically between 0.2 and 1.5 mm. The length "L" of
the slit cylinder 56 would typically be between 5 and 10 mm. What
is most important is that the length "L" should not be more than
10% as long as the guiding catheter 40 and ideally the length "L"
is less than 1% as long as the guiding catheter 40. The shorter the
length, the less will be the frictional force against the interior
wall of the guiding catheter 40. The ideal material for the slit
cylinder 56 is a shape memory alloy and the ideal shape memory
alloy would be super elastic Nitinol.
[0032] As seen in FIGS. 4, 5 and 6, the expandable legs 54 with
radiopaque feet 55 are joined to slit cylinder 56. The feet 55 (as
well as other parts of the ostial stent positioner 50) could be
made radiopaque by plating with a highly radiopaque metal such as
platinum, gold or tantalum or they could be made from a high
density metal. An important feature of the ostial stent positioner
50 is that the angle "A" of the slit cylinder 56 as shown in FIG. 6
is approximately 20 degrees and certainly less than 30 degrees.
This small angle allows the ostial stent positioner 50 to be back
loaded into the guiding catheter 40 without requiring a special
introducer device as was described in a prior application.
Furthermore, if the interventional cardiologist accidentally
advances the slit cylinder 56 beyond the distal end of the guiding
catheter 40, the ostial stent positioner 50 can be readily pulled
back into the guiding catheter 40. Therefore, the designs shown in
FIGS. 4, 5, and 6 are an improvement over prior designs because the
ostial stent positioner 50 is easier to place into the guiding
catheter 40 without requiring an additional introducer tool and
without requiring an additional step in the method for placing a
stent at the ostium of an artery.
[0033] To introduce a stent delivery system into a coronary artery,
the typical diameter for the guiding catheter 40 would be 6, 7 or 8
French (Fr). It would be highly desirable for the ostial stent
positioner 50 to be made with a single diameter of its slit
cylinder 56 that holds the expandable legs 54. This would decrease
the inventory requirements for the positioner 50 for each
catheterization lab that performs coronary interventions.
Specifically, only one diameter of the slit cylinder 56 would be
required and it would fit into guiding catheters that are either 6,
7 or 8 Fr. It would also be highly desirable to have the cylinder
56 (as shown in FIGS. 4, 5 and 6) expand radially outward to gently
press against the inner surface of the guiding catheter 40. To have
a single product that would be suitable for 6, 7 or 8 Fr guiding
catheters, the outer diameter of the slit cylinder 56 when free in
air should be approximately the inside diameter of an 8 Fr guiding
catheter. Such a cylinder 56 would then also fit snugly within
either 6 Fr or 7 Fr guiding catheters. The wall thickness for the
slit cylinder 56 would ideally be between 0.001 and 0.003
inches.
[0034] It should also be understood that a larger diameter guiding
catheter 40 could be used specifically for treating an ostial
stenosis in a renal artery. Guiding catheters as large as 14 Fr or
as small as 6 Fr could be used for inserting a stent into an ostial
stenosis of a renal artery. Of course, the uncompressed diameter of
the slit cylinder 56 must also be at least slightly larger than the
inside diameter of any such guiding catheter. Therefore, it should
be understood that the dimensions for the slit cylinder 56 should
be somewhat larger for renal stenoses as compared to the dimensions
that are optimum for stenoses of the coronary arteries. However,
the length of the slit cylinder 56 of such a ostial stent
positioner for stenting a renal ostial stenosis should be less than
10% of the length of the guiding catheter.
[0035] FIG. 7 is a perspective view of an alternative embodiment of
the invention, which is the ostial stent positioner 60. The
positioner 60 has a helical, flat wire, cylindrical body 66 that is
quite flexible because of its helical design. Legs 64 with
radiopaque feet 65 are attached at the distal end of the cylinder
60 and a wire 61 is attached at the proximal end of the cylinder
60. The dimensions and materials for the ostial stent positioner 60
are comparable to the dimensions and materials of the ostial stent
positioner 50.
[0036] The major advantages of the designs of the slit cylinder 56
and the helical cylinder 66 as compared to the invention of Saltiel
are at least two-fold: (1) the cylinders 56 and 66 are very short
compared to the length of the guiding catheter 40 so that they
slide easily within the guiding catheter 40; and (2) both the slit
cylinder 56 and the helical cylinder 66 are each radially
expandable, variable diameter cylinders so as to gently contact the
interior wall of the guiding catheter 40. The important
characteristic of the variable diameter cylinder 56 or 66 is that
its outside diameter becomes substantially equal to the inside
diameter of the guiding catheter into which the variable diameter
cylinder is inserted. Two advantages of the variable diameter
cylinder are that it allows for one-size-fits-all design to
decrease the inventory of the ostial stent positioners in any
catheterization lab and also, by being gently expanded against the
wall of the guiding catheter 40, these variable diameter cylinders
56 and 66 provide the largest interior lumen which facilitates the
introduction of the stent delivery system. The Saltiel invention
has a fixed diameter cylinder that extends for the entire length of
the guiding catheter and therefore a different size of ostial stent
positioner would be required for each different diameter of the
guiding catheter. An additional disadvantage of the Saltiel
invention is that the full length cylinder within the guiding
catheter would be very difficult to advance or pull back because
the frictional forces would be very large. In addition, there would
be severe limitations for radiopaque contrast injection through the
Saltiel device due to increased fluid impedance.
[0037] Another alternative embodiment of the present invention is
the ostial stent positioner 60 that is shown in FIG. 8. This
positioner 60 has a short distal wire section 61D, a much longer
proximal wire section 61P, a handle 62 and a short, slit, variable
diameter cylinder 63 having a multiplicity of legs 64 having
radiopaque feet 65. In FIG. 8, the direction of the longitudinal
axis of the positioner 60 is shown as the line 66. When deployed in
air, the angle "B" between the direction 66 and the long axis of
the feet 65 should be between 60 and 90 degrees. This is quite
different from the design of the positioner 50 where the angle "B"
is approximately 45 degrees. Having an angle "B" in air of at least
60 degrees provides better contact with the wall of the aorta when
the positioner 60 is pushed against that wall. The length L1 of the
variable diameter cylinder 63 should be between 0.5 and 3.0 cm. As
with the slit cylinder 56 of FIG. 6, the angle "A" should be about
20 degrees for easily pulling of the positioner 60 back into the
distal end of a guiding catheter.
[0038] An important improvement of the design of positioner 60 is
that there is a more flexible section 61D of the wire that moves
the cylinder 63 back and forth in the guiding catheter. The section
61D should have a length L2 that lies between 1 and 10 cm and
should have a wire diameter of between 0.01 and 0.02 inches. This
more flexible section prevents inadvertent bending of the curved
section of the guiding catheter when the positioner 60 extends out
the guiding catheter's distal end. The stiffer wire section 61P
provides improved pushability and should have a length L3 that lies
between 100 and 120 cm and should have a diameter that lies between
0.015 and 0.03 inches. The handle 62 should have a length L4 of at
least 3 cm and a diameter of at least 0.02 inches. The handle 62 is
optimally a plastic that has a bright color such as yellow, orange
or red that is different from the typical gray color of a guide
wire.
[0039] All other features of the design of the positioner 60 are
similar to those same features of the positioner 50 of FIGS. 4, 5
and 6.
[0040] An important aspect of the design of the ostial stent
positioner is that it should be coated with a lubricity agent to
ease its motion through the guiding catheter. Hydrophilic polymers
and silicone are examples of lubricity agents that could be used to
coat at least part of the ostial stent positioner.
[0041] Various other modifications, adaptations and alternative
designs are of course possible in light of the teachings as
presented herein. Therefore it should be understood that, while
still remaining within the scope and meaning of the appended
claims, this invention could be practiced in a manner other than
that which is specifically described herein.
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